The
feasibility of direct deposition of glycerol onto organic thin films to provide
enhanced secondary ion signals is investigated by C60+
cluster secondary ion mass spectrometry (SIMS). Glycerol drops were deposited
on various organic thin films and the organic molecules were rapidly
incorporated into the
drop via diffusion and convective forces. The
resulting glycerol/analyte drops were then probed
with fullerene primary ions under dynamic and static SIMS conditions. High
primary ion beam currents were shown to aid in the
mixing of the glycerol drop, thus replenishing the probed area and sustaining
secondary ion yields. Integrated molecular secondary ion signals for tetrabutylammonium iodide and cocaine in the glycerol drops
compared to an analogous area on the surface were enhanced by several orders of
magnitude (> 100x). These molecules were chosen because the molecular ions
are formed through separate ionization pathways. Once the analyte
of interest is incorporated into the glycerol microdrop,
the solution chemistry can be tailored, with examples shown for cyclotrimethylenetrinitramine
(RDX) chloride adduct formation. Additionally, depositing localized glycerol
drops may enhance analyte secondary ion count rates
to high enough levels to allow for site-specific chemical maps of molecules in
complex matrices such as biological tissues.